Some common WordPress errors:

1. Internal server error This error indicates that the server was unable to fulfill the request and is usually caused by conflicting plugin or theme functionality or corrupted browser cache.
2. Error establishing database connection This is a serious error indicating that WordPress cannot connect to the database. It may be caused by incorrect credentials, database corruption or server issues.
3. White Screen of Death (WSOD) This is a plain white screen with no error message, usually caused by a PHP or database error.
4. memory exhaustion error This error typically occurs when a plugin or script exceeds the default allocated memory limit.
5. 403 Prohibition error This issue occurs when the server believes that the user does not have permission to access the specified URL.
6. 404 Not found This error occurs when a visitor tries to access a page that does not exist, usually due to a broken link or a deleted page.
7. Image upload error This error may be encountered when uploading images through the media library.